Importance of telomerase

[Enzyme]

Hello and good morning (here in Spain it's 12:38, he he)!

[I'm new in this forum. Firstly of all, thanks for reading my post and sorry for my English, it is not good...]

Telomerase is an enzymatic complex (several proteins + one RNA) which controls the integrity and lenght of telomeres (highly repeated DNA regions, without codifying, located at the end of the chromosomes which avoid the degradation of them by enzymes and a possible telomeric fusion). Telomerase is active in cells with high skill of proliferation (embryonic and phoetal cells, tumor cells,...). It is very important in apoptosis, tumoration, etc.

Here is my doubt:

Why, if telomerase doesn't exist in the cell, can appear some diseases and patologies (due to the telomeres shortening, which carries chromosomic alterations) if normally telomerase is inactive in the cell, and the activity of this enzyme encourage the survivance and proliferation of cancer cells?.

I suppose that it can be related with a control (genetic control or another), if the enzyme is represed or activated. Is this right?

If you know something about this, could you tell me the process? I'm preparing a seminar for one subject of the career (Citogenetics) about telomerase and I need to clear my doubts, he he.

Nice to talk with you and sorry for my English again . See ya!

[sdekivit]

no telomerase = chromosome shortening = cell senescence because of phosphorylation of histone H2AX and activating the p53 signalling pathway by the kinase Chk2 and thus less pathologies because the cells don't divide anymore.

[Enzyme]

OK, a lot of thanks sdekivit.

But I have another question: If there isn't telomerase, telomeres can be fusioned or degradated. And telomerase is necessary for the cell. Cell cannot prescind of telomerase. I suppose that telomerase is represed in cells, but not absent. Is it right? Or only telomerase is synthetised when the cell needs it or when the cell receives a signal for transcription?

See ya!

[sdekivit]

i actually don't know the answer. Many research is still be done in this field of research. But it may be that telomerase has been supressed or inhibited. Maybe you should look for this topic in scientific articles for more info.

Good luck.

[Enzyme]

Yes, the research of telomerase is relatively young. We don't already know many aspects of this enzyme (processes, intervention, etc). I'll look for some articles.

Thank you anyway

[Jessieh04]

I am not sure i understand your questions. Are you a sking why is it if telomerase is not in the cell, can you get diseases (which are caused by the shortening of telomeres?)

here are a few sites and articles that you may find helpful, especially if you are doing a seminar:

http://www.pnas.org/cgi/content/abstract/94/20/10687
http://www.eurekalert.org/pub_releases/ ... 081403.php
http://www.clinchem.org/cgi/content/full/43/5/708

[Enzyme]

Jessieh04, thanks for the links (I'm taking them a look right now).

No, I'm trying to ask if telomerase is repressed in normal cells. Because if it is active, it is favourable to proliferation of tumor cells. But if telomerase doesn't intervent, telomeres can be fusioned or degradated.

But also I'm trying to ask if in a standard situation, as telomerase is inactive in the cell (I suposse, I don't know if telomerase is repressed normally, it is my first doubt), can you get diseases if telomerase is absent?

Do you understand me? (sorry for my English, it isn't good. I can't explain me correctly... )

[Poison]

It may not be the answer to your question, I may be misunderstood.
Telomere shortens every time the cell divides. This tells the cell when it is senescent (old) and the time to go through apoptosis. In cancer cells, telomere shortening does not appear. So they continuously divide, and does not become scenescent, means they don't go through apoptosis.

[Enzyme]

It may not be the answer to your question, I may be misunderstood.
Telomere shortens every time the cell divides. This tells the cell when it is senescent (old) and the time to go through apoptosis. In cancer cells, telomere shortening does not appear. So they continuously divide, and does not become scenescent, means they don't go through apoptosis.

Yes, I know cellular senescence is due to shortening of telomeres. So as tumor cells are continuously dividing, there isn't shortening of telomeres.

But I'm trying to ask another thing. After holidays I'll ask my doubts to my professor and also I'll continue looking for information in articles, books, etc to find the answer. I'll tell you when I know it .

Thank you anyway .